[U-Boot-Users] real tech in u-boot

Hello! I'm porting u-boot to smdk2800 board. The ethernet card, that we use is realtech8139D. U-boot recognizes the card, but when it tries to transmit the very first packet( after tftpboot command), it fails to do that. Can you give any idea of what could be the problem? Thank you. Kirnasov A.